• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.1
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• pp.33-41
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• 2012

A differential fault analysis(DFA) is one of the most important side channel attacks on block ciphers. Most block ciphers, such as DES, AES, ARIA, SEED and so on., have been analysed by this attack. PRESENT is a 64-bit block cipher with 80/128-bit secret keys and has a 31-round SP-network. So far, several DFAs on PRESENT have been proposed. These attacks recovered 80, 128-bit secret keys of PRESENT with 8~64 fault injections. respectively. In this paper, we propose an improved DFA on PRESENT-80/128. Our attack can reduce the complexity of exhaustive search of PRESENT-80(resp. 128) to on average 1.7(resp. $2^{22.3}$) with 2(resp. 3) fault injections, From these results, our attack results are superior to known DFAs on PRESENT.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.4
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• pp.231-239
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• 2007

This paper presents the trade-off relationship between area and performance in the hardware design space exploration for the Korean national standard 128-bit block cipher algorithm SEED. In this paper, we compare the following four hardware design types of SEED algorithm : (1) Design 1 that is 16 round fully pipelining approach, (2) Design 2 that is a one round looping approach, (3) Design 3 that is a G function sharing and looping approach, and (4) Design 4 that is one round with internal 3 stage pipelining approach. The Design 1, Design 2, and Design 3 are the existing design approaches while the Design 4 is the newly proposed design in this paper. Our new design employs the pipeline between three G-functions and adders consisting of a F function, which results in the less area requirement than Design 2 and achieves the higher performance than Design 2 and Design 3 due to pipelining and module sharing techniques. We design and implement all the comparing four approaches with real hardware targeting FPGA for the purpose of exact performance and area analysis. The experimental results show that Design 4 has the highest performance except Design 1 which pursues very aggressive parallelism at the expanse of area. Our proposed design (Design 4) shows the best throughput/area ratio among all the alternatives by 2.8 times. Therefore, our new design for SEED is the most efficient design comparing with the existing designs.

• Convergence Security Journal
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• v.18 no.4
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• pp.27-33
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• 2018

Stream cipher is an one-time-pad type encryption algorithm that encrypt plaintext using simple operation such as XOR with random stream of bits (or characters) as symmetric key and its security depends on the randomness of used stream. Therefore we can design more secure stream cipher algorithm by using mathematical analysis of the stream such as period, linear complexity, non-linearity, correlation-immunity, etc. The key stream in stream cipher is generated in linear feedback shift register(LFSR) having characteristic polynomial. The primitive polynomial is the characteristic polynomial which has the best security property. It is used widely not only in stream cipher but also in SEED, a block cipher using 8-degree primitive polynomial, and in Chor-Rivest(CR) cipher, a public-key cryptosystem using 24-degree primitive polynomial. In this paper we present the concept and various properties of primitive polynomials in Galois field and prove the theorem finding the number of irreducible polynomials and primitive polynomials over $F_p$ when p is larger than 2. This kind of research can be the foundation of finding primitive polynomials of higher security and developing new cipher algorithms using them.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.7
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• pp.402-413
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• 2004

This paper presents an Implementation of Korean standard 128-bit block cipher SEED for the small (8 or 16-bits) embedded system using a low-cost FPGA(Field Programmable Gate Array) chip. Due to their limited computing and storage capacities most of the 8-bits/16-bits small embedded systems require a separate and dedicated cryptography processor for data encryption and decryption process which require relatively heavy computation job. So, in order to integrate the SEED with other logic circuit block in a single chip we need to invent a design which minimizes the area demand while maintaining the proper performance. But, the straight-forward mapping of the SEED specification into hardware design results in exceedingly large circuit area for a low-cost FPGA capacity. Therefore, in this paper we present a design which maximize the resource sharing and utilizing the modern FPGA features to reduce the area demand resulting in the successful implementation of the SEED plus interface logic with single low-cost FPGA. We achieved 66% area accupation by our SEED design for the XC2S100 (a Spartan-II series FPGA from Xilinx) and data throughput more than 66Mbps. This Performance is sufficient for the small scale embedded system while achieving tight area requirement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4A
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• pp.291-300
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• 2002

In this paper, a way of constituting optimized S box and G function was suggested in the block cipher whose structure is similar to SEED, which is KOREA standard of 128-bit block cipher. S box can be formed with nonlinear function and an affine transform. Nonlinear function must be strong with differential attack and linear attack, and it consists of an inverse number over GF(2$\^$8/) which has neither a fixed point, whose input and output are the same except 0 and 1, nor an opposite flexed number, whose output is one's complement of the input. Affine transform can be constituted so that the input/output correlation can be the lowest and there can be no fixed point or opposite fixed point. G function undergoes diffusive linear transform with 4 S-box outputs using the matrix of 4$\times$4 over GF(2$\^$8/). G function can be constituted so that MDS(Maximum Distance Separable) code can be formed, SAC(Strict Avalanche Criterion) can be met, there can be no weak input, where a fried point, an opposite fried point, and output can be two's complement of input, and the construction of hardware can be made easy. The S box and G function suggested in this paper can be used as a constituent of the block cipher with high security, in that they are strong with differential attack and linear attack with no weak input and they are excellent at diffusion.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.205-207
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• 2003

본 논문에서는 국내 표준 128비트 블록 암호화 알고리즘인 SEED와 UART를 통합하여 최저가의 FPGA로 구현하는 방법을 제안한다. 논문[11베서 구현한 면적 요구량이 최소로 구현된 SEED암호화 모듈의 유용성을 실제 내장형 시스템에 적응하여 그 실효성을 보여주는 것이 본 논문의 목적이다. 우리가 구현한 회로는 SEED 를 통해 암호화를 한 후 UART를 이용하여 외부와의 통신할 수도 있고, SEED를 건너뛰고 UART 단독만 이웅하여 외부와 통신을 할 수도 있다. 또한, SEED 자체를 coprocessor로 이용하여 암호화/복호화 가능만 사용할 수도 있도록 설계하였다. 구현 결과, 10만 게이트를 갖는 Xilinx사의 Spartan-ll 계열의 xc2s100시리 즈 칩을 사용하였을 때, SEED와 UART와 주변 논리 회로를 합하여 84% 이하의 면적을 차지 하였고, 최대 41.3Mhz클럭에서 동작하였으며, SEED의 암호화 처리 Througput은 54.SSMbps로서 UART를 이용하여 통신하는데 전혀 문제가 없었다.

• ETRI Journal
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• v.33 no.2
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• pp.267-274
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• 2011

This paper proposes an efficient masking method for the block cipher SEED that is standardized in Korea. The nonlinear parts of SEED consist of two S-boxes and modular additions. However, the masked version of these nonlinear parts requires excessive RAM usage and a large number of operations. Protecting SEED by the general masking method requires 512 bytes of RAM corresponding to masked S-boxes and a large number of operations corresponding to the masked addition. This paper proposes a new-style masked S-box which can reduce the amount of operations of the masking addition process as well as the RAM usage. The proposed masked SEED, equipped with the new-style masked S-box, reduces the RAM requirements to 288 bytes, and it also reduces the processing time by 38% compared with the masked SEED using the general masked S-box. The proposed method also applies to other block ciphers with the same nonlinear operations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.291-297
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• 2006

This paper describes the architecture for reducing its size and increasing the computation rate in implementing the SEED algorithm of a 128-bit block cipher, and the result of the circuit design. In order to increase the computation rate, it is used the architecture of the pipelined systolic array. This architecture is a simple thing without involving any buffer at the input and output part. By this circuit, it can be recorded 320 Mbps encryption rate at 10 MHz clock. We designed the circuits with goals of the high-speed computations and the simplified structures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.1
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• pp.123-136
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• 2004

In this paper, complexity and regularity of polynomial multiplication over $GF({2^n})$ are defined by using Hamming weight of rows and columns of the matrix ever GF(2) which represents polynomial multiplication. It is shown experimentally that in order to construct the block cipher robust against differential cryptanalysis, polynomial multiplication of substitution layer and the permutation layer should have high complexity and high regularity. With result of the experiment, a way of constituting S box and G function is suggested in the block cipher whose structure is similar to SEED, which is KOREA standard of 128-bit block cipher. S box can be formed with a nonlinear function and an affine transform. Nonlinear function must be strong with differential attack and linear attack, and it consists of an inverse number over $GF({2^8})$ which has neither a fixed pout, whose input and output are the same except 0 and 1, nor an opposite fixed number, whose output is one`s complement of the input. Affine transform can be constituted so that the input/output correlation can be the lowest and there can be no fixed point or opposite fixed point. G function undergoes linear transform with 4 S-box outputs using the matrix of 4${\times}$4 over $GF({2^8})$. The components in the matrix of linear transformation have high complexity and high regularity. Furthermore, G function can be constituted so that MDS(Maximum Distance Separable) code can be formed, SAC(Strict Avalanche Criterion) can be met, and there can be no weak input where a fixed point an opposite fixed point, and output can be two`s complement of input. The primitive polynomials of nonlinear function affine transform and linear transformation are different each other. The S box and G function suggested in this paper can be used as a constituent of the block cipher with high security, in that they are strong with differential attack and linear attack with no weak input and they are excellent at diffusion.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.1937-1940
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• 2003

정보보호 평가는 크게 시스템 평가인 CC(Common Criteria)평가와 암호모듈 평가인 CMVP(Cryptographic Module Validation Program)평가로 나눌 수 있다. 본 논문은 국내 표준 암호 알고리즘 SEED를 북미의 CMVP의 3가지 블록 알고리즘 시험방법인 KAT(Known Answer Test), MCT(Monte C미개 Test), MMT(Multi-block Message Test)를 JAVA환경에 적용하여 시범 구현하였다. 테스트 방법으로 CMVP의 MOVS, TMOVS, AESAVS를 선정하여 FIPS 표준을 적용하였다. 구현 환경으로는 JCE기반의 Cryptix를 채택하여 CMVP의 블록 암호 알고리즘 테스트 시스템 중 일부를 구현하였다.